1. Field Of the Invention
The present invention relates warp knitting machines having (a) a main shaft driven by an electrical main motor, (b) an electrically operated brake activated upon current interruption, and (c) at least one supplemental electrical system connected to the main power circuit, for influencing the thread feed.
2. Description Of Related Art
When a warp knitting machine of the foregoing type (DE PS 30 25 792) is switched, the supplemental control system is separated from the power mains by a time delay relay, so that the supplemental system operates until the actual standstill of the main shaft. However, if power mains fail both the main shaft motor as well as the supplemental system lose power. While inertia causes the main shaft to runs on, immediate inoperability befalls the supplemental system, that is, the controlling motor for the warp beam drive speed and a jacquard arrangement. The main shaft is not considered a substantial problem since the brake on the main shaft operates quite rapidly, that is, within one or two revolutions. The thus resulting pattern errors are not observable to the naked eye.
Generally speaking, guide bars are mechanically connected to the main shaft, suitably by means of a cam plate system or pattern chains. Thus, after the run down of the main shaft, the correct correspondence between the guides and the remaining operating elements remains. It is however, burdensome to alter such displacement patterns since this requires an exchange of cam plates or pattern chains. It is thus either impossible or rather difficult to provide a displacement pattern with a longer repeat.
A control arrangement for the displacement of guide bars in warp knitting machines is known (DE OS 22 57 224), in which the displacement steps to be taken are read off from a schedule carrier, for example a punched or magnetic tape. A synchronizing transmitter generates a signal in particular angular positions of the main shaft, based on which, the most recently read displacement step is carried out by means of a position control circuit. By using another schedule carrier, it is possible to change the pattern by changing the displacement motion. The progress of the displacement motion cannot be controlled since it depends upon the design of the control circuit.
Accordingly, there is a need for a warp knitting machine of the above-mentioned type in which the displacement pattern for the guide bars may be altered in a simple and procedurally safe manner.